1. Field of the Invention
The present invention relates to a vehicle presence alert apparatus for informing the presence of a vehicle.
2. Description of Related Art
Vehicles driven by an electric motor such as electric vehicles and hybrid vehicles are increasing recently. Because a vehicle driven by an electric motor travels quietly as compared to a vehicle driven by an internal combustion engine, a pedestrian or the like may not notice the presence of the vehicle. In this relation, a vehicle presence alert apparatus is known. A conventional vehicle presence alert apparatus emits an alert sound such as pseudo engine sound and the like from a speaker mounted to the vehicle, thereby alerting a pedestrian or the like in front of the vehicle to the presence of the vehicle (see JP-H10-201001A and JP-2006-199110A corresponding US-2007/0257783A for instance).
If an alert sound is emitted in a simple way, because the alert sound is diffused to the environment and attenuated, a high capacity speaker is required to alert the environment to the presence of the vehicle. However, it is typically difficult to mount the high capacity speaker to the vehicle. Moreover, if the high capacity speaker is used to emit an alert sound, a person (e.g., a passenger in a vehicle compartment) who needs not to recognize the presence of the vehicle may hear the alert sound and may have an uncomfortable feeling.
JP-2007-182195A discloses a vehicle presence alert system including a vehicle presence alert apparatus mounted to a vehicle and a notification apparatus wearable by a pedestrian. The vehicle presence alert apparatus transmits radio wave for alert in addition to the alert sound. The notification apparatus worn by the pedestrian receives the radio wave for alert and causes the pedestrian to tactilely or visually recognize the presence of the vehicle. In order for the vehicle presence alert system to enable the recognition of the presence of the vehicle, the vehicle needs to have a transmitter for transmitting the radio wave. Further, a pedestrian and the like need to wear a receiver for receiving the radio wave and a perception device for operating in response to the reception of the radio wave. Thus, the above vehicle presence alert system involves complicated and inconvenient management.